Arylation of [60]Fullerene with Br₂/FeCl₃/PhH: Formation of C₅₈ Derivatives via CO Loss

Abstract

Heating a mixture of [60]fullerene, bromine, ferric chloride and benzene under reflux for 24 h products a range of phenylated [60]fullerene derivatives. The main product is C₆₀Ph₅H but other components identified by mass spectrometry (and in some cases separated by HPLC) are: C_6oPh _n (n = 4, 6, 8, 10, 12), C₆₀Ph _n O₂(n = 4, 6, 8, 10, 12), C₆₀Ph _n OH (n = 7, 9, 11), C₆₀Ph _n H₂ (n = 4, 10), C₆₀Ph₄H₄, C₆₀Ph₅H₃, C₆₀Ph _n 0₂H (n = 5, 9), C₆₀Ph₄C₆H₄O₂, C₆₀Ph₉OH₃, and C₆₀Ph₁₁ O₃H₂. In the corresponding reaction with toluene, the crude reaction mixture contained C₆₀(MeC₆H₄)₄ as a main product; C₆₀(ClC₆H₄)₅H was obtained from the reaction with chlorobenzene. Formation of these derivatives is believed to involve radical bromination of the fullerene, followed by electrophilic substitution of the hatogenofullerene into the aromatic, accompanied in some case by hydrolysis, elimination and epoxide formation; oxidation may also introduce ketone/dioxetane functionality. The EI mass spectra of C₆₀Ph₄O₂ and C₆₀Ph₈O₂show degradation to C₅₈Ph _n (n = 0–8), having structures believed to be related to the pseudofollerenes C₆₈Ph _n (n = 0–8) reported recently. These results suggest that some derivatisations of fullerenes confer stability, due to the relief of strain.